I. Technical Field
The present invention relates to a lens drive apparatus which employs a threaded engagement structure composed of a lead screw and a nut to drive a lens frame holding a lens along an optical axis.
II. Description of the Related Art
A conventional lens drive apparatus comprises a base, a lens frame holding a lens, two guide shafts which are secured to the base on both sides holding the lens so as to guide the lens frame along an optical axis, a motor secured to the base, a lead screw which is directly connected to the motor and driven thereby to rotate, a nut which is held by the lens frame so as to threadably engage the lead screw, a coil spring for urging the lens frame toward the nut, and the like as described in Japanese Patent Application Laid-Open No. 2004-34139 and Japanese Patent Application Laid-Open No. 2006-114117, for example. In such an apparatus, the motor rotates the lead screw, so as to screw-feed the nut, thereby moving the lens frame along the optical axis.